This invention generally relates to power closure systems for vehicles. More particularly, this invention relates to obtaining initialization information for controlling movement of the position of a vehicle panel that can be automatically closed by a power closure system.
Power closure systems are used on vehicles for power sliding doors and power lift gates, for example. Typical arrangements have a clutch to selectively establish a mechanical coupling between an actuator such as a motor and the door or lift gate. The motor control arrangement typically includes a position sensor that monitors the position of the door during a power closure. Typical arrangements include xe2x80x9crelativexe2x80x9d position sensors such as encoders or Hall effect sensors associated with a rotating armature. Such relative sensors cannot tell absolute position and, therefore, techniques must be employed to achieve accurate position information for use during a power closure. It is necessary to initialize the position information from the sensor when the actual door or lift gate position is known.
Conventional techniques include initializing the position when the door or lift gate is closed. In conventional arrangements, however, the clutch is disengaged when the door is closed and the closure system is not in a state that accurately represents an operating state. For example, wire play and gear backlash occur because the system is no longer under tension once the clutch is disengaged. After this, there is not a proper correlation between the sensor position and the door or lift gate position. Therefore, position initialization is not accurate or reliable with such an approach.
This invention provides improved position initialization, in part, by eliminating any slack in the coupling between the motor and the door or lift gate prior to determining the initialization position information.
In general terms, this invention is a position initialization system and method for accurately initializing a sensor position so that an absolute position of a moveable panel on a vehicle can be determined.
An example system designed according to this invention includes a motor that provides the force for moving the moveable panel (i.e., the door or lift gate). A coupling couples the motor to the panel and includes a varying tension between the motor and the panel, depending on the operating state of the system. A position sensor is associated with a coupling and provides an indication of the panel position. An indicator provides an indication when the panel is in a closed position. A controller energizes the motor responsive to the closed position indication to urge the panel toward the closed position to reduce any slack between the motor and the panel. The controller obtains an initialization position indication from the position sensor when there is no slack.
A method according to this invention includes several steps. An example method includes determining that the panel is in a closed position. Then the motor is energized to urge the panel toward the closed position to reduce any slack between the motor and the panel. The initialization position is determined when there is no slack.
In one example arrangement designed according to this invention, the motor operates at a selected torque during the slack reduction process. The selected torque preferably corresponds to the operating torque of the motor while moving the panel from an open position to a closed position. In one example, the selected torque is determined as an average torque between two selected points along the panel travel from the open position to the closed position.
In one example, a controller determines the appropriate motor torque only when the motor has not stalled or the panel has not encountered any obstructions while moving between the two selected points.
The various features and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the currently preferred embodiments. The drawings that accompany the detailed description can be briefly described as follows.